1. Field of the Invention
The present invention relates to: a carboxamide derivative having reduced amide ester content; an efficient production method thereof; and a detergent composition including the carboxamide derivative produced by the production method and having excellent low-temperature stability.
2. Description of the Related Art
Carboxamide is used in a hair conditioner, and it is used as an intermediate of a carboxamide derivative such as amide betaine and amidoamine oxide. In particular, a carboxamide derivative is widely used for cleaning agents such as hair shampoo and dishwashing detergent, cosmetic materials and beauty products since it is less irritating to the skin and has favorable biodegradability.
Carboxamide is usually produced by condensing a fatty acid or an ester thereof with a diamine at a reaction temperature of 80° C. to 200° C. and under a normal or reduced pressure. Also, it is known that an amidoamine oxide as a carboxamide derivative may be obtained by oxidizing carboxamide with hydrogen peroxide, and it is known that amide betaine as a carboxamide derivative may be obtained by reaction of carboxamide with monohaloalkylcarboxylic acid and a salt thereof.
For example, it is considered that the amount of diamine used for the production of highly pure carboxamide is preferably 0.83 times by mole to 1.25 times by mole, and more preferably 1.0 times by mole to 1.2 times by mole, with respect to that of a fatty acid or an ester thereof (paragraph 0017 in Japanese Patent Application Laid-Open (JP-A) No. 11-349542). Also, it is known that an addition of organic phosphonic acid in producing amidoamine oxide yields a composition including amidoamine oxide having superior preservation stability at a high temperature of 50° C. in terms of color and odor (paragraphs 0022 and 0023 in JP-A No. 11-152260).
However, sedimentation occurs during low-temperature preservation of amidoamine oxide, which is obtained by reacting hydrogen peroxide with carboxamide obtained by reacting a fatty acid ester with 1.20 times by mole or less with respect to the fatty acid ester of a diamine, and amino betaine, which is obtained by reacting the carboxamide with a monohaloalkylcarboxylic acid or a salt thereof. This causes problems such as decreased commercial value of amidoamine oxide and amide betaine as well as reduced low-temperature stability of a detergent composition which uses thereof.